Archaeologists have linked rising and lowering sea levels in the Atlantic Ocean to the ebbs and flows of ancient civilizations in southern Brazil.
The findings, which incorporate several lines of past archaeological evidence, suggest even large, resilient, and cooperative coastal communities can easily go out with the tide.
When analyzing and dating a series of prehistoric shell 'mountains', known as sambaquis in the local language, researchers noticed some significant changes in southwestern Brazil about 2,500 years ago.
At this time, the size and frequency of sambaqui sites suddenly began to decrease, possibly indicating the dissolution of what were, for millennia, dense and stable shellfish-eating populations.
Other research in the area has also identified a rapid reduction in sambaquis around this time, but some researchers think these changes mostly occurred from the rise of ceramics and crops. The use of this new technology meant populations didn't need to rely as much on fish or mollusks, leading to a reduction in shell piles.
However, the new study found the decline of shell middens started before the introduction of pottery. So why, then, were sambaqui practices abandoned?
The answer might have to do with an extreme, retreating tide. By reassessing human and animal remains from Babitonga Bay – home to Brazil's largest concentration of sambaquis – researchers have put forward a new timeline.
According to more than 400 radiocarbon dates, the spread of ceramics in Babitonga probably started around 1,200 years ago. READ MORE...
If it wasn't for an extinct relative of modern humans known as the Denisovans, some researchers suspect our own species might never have made their home on the highest and largest plateau in the world.
The Tibetan Plateau, sometimes called the Himalayan Plateau, is nicknamed 'the roof of the world' because it sits, on average, 4,000 meters (13,000 feet) above sea level.
This vast sweep of elevated land, which covers most of Tibet, along with parts of China, India, Pakistan, and several other countries in the region, is usually considered one of the last places that Homo sapiens settled permanently. Studies suggest there have been periods of occupation by various ancestors taking place over the past 160,000 years, but gaps in the record are hard to interpret.
Have there always been people up on the roof of the world, or is each period a resettlement by a new community?
A geneticist and an archaeologist have now suggested another timeline that works just as well with the limited evidence we have on hand.
The researchers incorporated both archaeological and genetic evidence to develop two, contrasting models of occupation: one continuous and one divided up over time. Crucially, the two models can be tested, potentially telling us one day how far back modern populations stretch.
In the discontinuous model, humans visited on and off for tens of thousands of years, until finally staying put around 9,000 years ago.
Alternatively, current evidence could also support permanent colonization that began on the plateau between 30,000 and 40,000 years ago. If so, the long genetic lineage might have passed on some helpful tricks for living up where the air is thin.
According to recent DNA analyses, a single crossbreeding event between Denisovans and H. sapiens in East Asia, no sooner than 46,000 years ago, might have infused our species with the genes they needed to make their home in such a low oxygen environment. READ MORE...
